ABSTRACT:

The Caspar Creek Experimental Watersheds (CCEW) are a long-term USDA Forest Service research site located near Fort Bragg, California in the Jackson Demonstration State Forest. The CCEW consists of two experimental watersheds: the North Fork (479 ha) and the South Fork (417 ha). Since 1962, the US Forest Service Pacific Southwest Research Station has been collecting measurements of precipitation, streamflow, and sediment transport; these data are maintained and archived by the USFS. Since their establishment, three timber harvesting experiments have been conducted at the CCEW.
The first experimental harvest (Phase 1) was a selective cut (66% removal of pre-treatment basal area) conducted in the South Fork watershed using tractor yarding in the early 1970s. Phase 1 of the project includes data from 1962 to 1985. Gauging stations were added in 12 sub-watersheds of the North Fork by 1985 in preparation for the second experimental harvest (Phase 2). Phase 2 of the project includes data from 1985 to 2017. From 1985 to 1992, roughly half of the North Fork watershed was clearcut, mainly using cable yarding, and following the newly-enacted Forest Practice Rules. Two additional gauges were added in North Fork sub-watersheds in 1999 and 2001. Gauging stations were added in 10 sub-watersheds of the South Fork in 2000 in preparation for a third harvesting experiment (Phase 3). Logging for the third harvest occurred in 2017-2019 in the South Fork watershed.

This data publication contains soil volumetric water content values (cm3 cm-3) at 15, 30, and 100 cm soil depth in three South Fork Caspar Creek sub-watersheds. Measurements were collected from one transect in each subcatchment, which consisted of plots at five hillslope positions—riparian, toeslope, sideslope, shoulder, and ridge (15 sample plots total). Samples were collected at 10 minute intervals using METER EC5 sensors (METER Group, Inc., Pullman, WA, USA; resolution: 0.001 m3 m-3; accuracy +/- 0.03 m3 m-3) vertically into the soil. Measurements start in fall 2015 extend to July 31, 2018. Specifically, the measurements were collected from Treat (TRE; 14 ha); Williams (WIL; 26 ha), and Ziemer (ZIE; 26 ha).

Vegetation in the South Fork is dominated by third-growth coast redwood (Sequoia sempervirens (D. Don) Endl.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), grand fir (Abies grandis (Doug. ex D. Don) Lindl.), and western hemlock (Tsuga heterophylla (Raf.) Sarg.), with smaller amounts of tanoak (Lithocarpus densiflorus (Fook. and Arn.) Rohn) and red alder (Alnus rubus Bong.). Soils in the sub-basin are predominately well-drained clay-loam Ultisols and Alfisols derived from Franciscan sandstones and shales.